The effect of spatial frequency and face inversion on facial expression processing in children with autism spectrum disorder

To investigate whether facial expression processing in children with autism spectrum disorder (ASD) is based on local information of the stimuli, we prepared low spatial frequency (LSF) images with blurred facial features and high spatial frequency (HSF) images with rich facial features from broad (normal) spatial frequency (BSF) images. Eighteen children with ASD (mean age 11.9 years) and 19 typically developing (TD) children (mean age 11.4 years) matched on non-verbal IQ were presented these stimuli in upright and inverted orientations. Children with ASD had difficulty in processing facial expressions from BSF and LSF images, but not from HSF images. In addition, BSF and HSF images elicited the inversion effect in TD children, but not in children with ASD. By contrast, LSF images elicited the inversion effect in both groups of children. These results suggest that children with ASD are biased toward processing facial expression based on local information, even though their capacity to process facial expressions configurally is spared.